/**
* This function obtains a queued task from the pool and returns it.
* If no such task is available the operation blocks.
*
* @param pool The thread pool structure.
* @return A task or NULL on error (or if thread pool should shut down).
*/
static struct threadpool_task* threadpool_task_get_task(struct threadpool *pool)
{
struct threadpool_task* task;
/* Obtain a task */
if (pthread_mutex_lock(&(pool->mutex))) {
perror("pthread_mutex_lock: ");
return NULL;
}
while (threadpool_queue_is_empty(&(pool->tasks_queue))) {
if (pool->stop_flag)
{
if (pthread_cond_broadcast(&(pool->cond))) {
perror("pthread_cond_broadcast: ");
}
if (pthread_mutex_unlock(&(pool->mutex))) {
perror("pthread_mutex_unlock: ");
return NULL;
}
return NULL;
}
/* Block until a new task arrives. */
if (pthread_cond_wait(&(pool->cond),&(pool->mutex))) {
perror("pthread_cond_wait: ");
if (pthread_mutex_unlock(&(pool->mutex))) {
perror("pthread_mutex_unlock: ");
}
return NULL;
}
}
if ((task = (struct threadpool_task*)threadpool_queue_dequeue(&(pool->tasks_queue))) == NULL) {
/* Since task is NULL returning task will return NULL as required. */
REPORT_ERROR("Failed to obtain a task from the jobs queue.");
}
if (pthread_mutex_unlock(&(pool->mutex))) {
perror("pthread_mutex_unlock: ");
return NULL;
}
return task;
}
static struct threadpool_task* threadpool_task_get_task(struct threadpool *pool)
{
struct threadpool_task* task;
if (pthread_mutex_lock(&(pool->mutex))) {
perror("pthread_mutex_lock: ");
return NULL;
}
while (threadpool_queue_is_empty(&(pool->tasks_queue))) {
if (pool->stop_flag)
{
if (pthread_cond_broadcast(&(pool->cond))) {
perror("pthread_cond_broadcast: ");
}
if (pthread_mutex_unlock(&(pool->mutex))) {
perror("pthread_mutex_unlock: ");
return NULL;
}
return NULL;
}
if (pthread_cond_wait(&(pool->cond),&(pool->mutex))) {
perror("pthread_cond_wait: ");
if (pthread_mutex_unlock(&(pool->mutex))) {
perror("pthread_mutex_unlock: ");
}
return NULL;
}
}
if ((task = (struct threadpool_task*)threadpool_queue_dequeue(&(pool->tasks_queue))) == NULL) {
DEMO_THREAD_Print("Failed to obtain a task from the jobs queue.");
}
if (pthread_mutex_unlock(&(pool->mutex))) {
perror("pthread_mutex_unlock: ");
return NULL;
}
return task;
}
int threadpool_add_task(struct threadpool *pool, void (*routine)(void*), void *data, int blocking)
{
struct threadpool_task *task;
if (pool == NULL) {
REPORT_ERROR("The threadpool received as argument is NULL.");
return -1;
}
if (pthread_mutex_lock(&(pool->free_tasks_mutex))) {
perror("pthread_mutex_lock: ");
return -1;
}
/* Check if the free task queue is empty. */
while (threadpool_queue_is_empty(&(pool->free_tasks_queue))) {
if (!blocking) {
/* Return immediately if the command is non blocking. */
if (pthread_mutex_unlock(&(pool->free_tasks_mutex))) {
perror("pthread_mutex_unlock: ");
return -1;
}
return -2;
}
/* blocking is set to 1, wait until free_tasks queue has a task to obtain. */
if (pthread_cond_wait(&(pool->free_tasks_cond),&(pool->free_tasks_mutex))) {
perror("pthread_cond_wait: ");
if (pthread_mutex_unlock(&(pool->free_tasks_mutex))) {
perror("pthread_mutex_unlock: ");
}
return -1;
}
}
/* Obtain an empty task. */
if ((task = (struct threadpool_task*)threadpool_queue_dequeue(&(pool->free_tasks_queue))) == NULL) {
REPORT_ERROR("Failed to obtain an empty task from the free tasks queue.");
if (pthread_mutex_unlock(&(pool->free_tasks_mutex))) {
perror("pthread_mutex_unlock: ");
}
return -1;
}
if (pthread_mutex_unlock(&(pool->free_tasks_mutex))) {
perror("pthread_mutex_unlock: ");
return -1;
}
task->data = data;
task->routine_cb = routine;
/* Add the task, to the tasks queue. */
if (pthread_mutex_lock(&(pool->mutex))) {
perror("pthread_mutex_lock: ");
return -1;
}
if (threadpool_queue_enqueue(&(pool->tasks_queue),task)) {
REPORT_ERROR("Failed to add a new task to the tasks queue.");
if (pthread_mutex_unlock(&(pool->mutex))) {
perror("pthread_mutex_unlock: ");
}
return -1;
}
if (threadpool_queue_getsize(&(pool->tasks_queue)) == 1) {
/* Notify all worker threads that there are new jobs. */
if (pthread_cond_broadcast(&(pool->cond))) {
perror("pthread_cond_broadcast: ");
if (pthread_mutex_unlock(&(pool->mutex))) {
perror("pthread_mutex_unlock: ");
}
return -1;
}
}
if (pthread_mutex_unlock(&(pool->mutex))) {
perror("pthread_mutex_unlock: ");
return -1;
}
return 0;
}
